The size of the prefrontal cortex has increased dramatically in primates compared to other vertebrates and its evolutionary expansion mirrors the development of attention, memory, and executive function in these species. Developmentally, the prefrontal cortex undergoes a long maturation process that extends through puberty and into early adulthood. A number of mental illnesses have onsets linked to the maturation of the prefrontal cortex, most notably schizophrenia, which manifests itself in early adulthood. Impulse control also improves in adulthood, and failure to develop adequately is associated with delinquency, drug abuse, and other conditions of health and social significance. Little is known about the physiological changes that the prefrontal cortex undergoes during puberty and early adulthood so as to mediate increased cognitive control. Taking advantage of recent methodological and conceptual advances, we propose to investigate the changes of prefrontal cortical physiology and functional connectivity that occur after puberty. We propose to use a non-human primate model which will allow us to conduct neurophysiological recordings in the prefrontal cortex of juvenile and adult animals. Our studies will also sample the posterior parietal cortex, an area interconnected with the prefrontal cortex. This will serve as a control area allowing us to determine what is unique about the maturation of the prefrontal cortex, and it will also allow us to study changes of functional connectivity between the prefrontal cortex and posterior parietal cortex. Our study will make use of monkeys trained to perform behavioral tasks that require attention, working memory, and executive control. These experiments will offer insights on how development of the prefrontal cortex alters its physiological responses which will be essential for understanding and treating mental illnesses associated with problems of prefrontal cortical maturation.